Various electrode configurations have been described for portable, baited, shock-producing animal deterrent devices.
U.S. Pat. No. 922,377 to Ames (1909), shows an animal extermination device with the electrodes being two concentric, curved, metal plates which surround the bait. These electrodes are essentially in the same plane and so they do not protect the bait from an approach from the top. The device described by Ames is designed for small rodents and the like and is very large relative to the target animal. Using the electrode configuration as described by Ames on a device that is very small relative to the target animal would allow the animal to reach the bait without touching the electrodes since the bait is not protected from an approach from the top. Also, the chance of a deer contacting both electrodes as shown by Ames is greatly reduced by their smooth surface and the lack of any protruding electrodes.
Swiss Patent 82,560 to Baumann (1919) shows a device very similar to the device shown by Ames with the electrodes being two flat, concentric metal plates arranged in the same plane. This device has the same problems as the device described by Ames.
A device to train animals using an electric shock, with or without bait, is described in U.S. Pat. No. 4,630,571 to Palmer (1986), which uses the conductive outer case of the device as one electrode and the earth as the other. This electrode configuration is very ineffectual because the chance of a pest animal contacting the smooth surface of the outer case is greatly reduced by the lack of protruding electrodes. Also, the operation of this device is dependent upon the moisture content of the soil which serves as the other electrode.
A baited shock-producing device to control deer in yards and gardens has been described in U.S. Pat. No. 5,894,818 to Betzen (1999) in which the electrodes meant to contact the deer's nose and deliver the deterrent voltage are shown as short projections above the top surface of the device. These electrodes are not effective because the possibility of a deer contacting the electrodes is reduced by their short length.
Subsequent prototypes and commercial models of Betzen's device have used two crisscrossing semicircular electrodes projecting from the top of the protective housing for the electronic components. These semicircular electrodes extend over the top of a scent dispenser which releases a perfumed oil to attract the deer to touch the device. This configuration of electrodes, while much more effective than those shown in the patent to Betzen (1999), must be approached from near the top to be effective. With this semicircular arrangement of electrodes, the probability of a deer contacting both electrodes simultaneously is dependent upon the height and the angle of the device and the size and the approach of the deer.
The prior art devices disclosed herein do not provide an electrode arrangement for a baited, shock-producing deer repellent device which completely surrounds the scent source and which therefore improves the chances of a deer contacting the electrodes, regardless of the height or angle of the device or the size or approach of the deer.